Abstract: Because standard reference wave-front is not needed in lateral shearing interferometry(LSI), interferometry cavity can be shorten, even absolute common path interferometry could be achieved, and it is immunity to air turbulence and vibration. Therefore, non-common path error between two shearing wave-fronts which come through different cubic prisms, shear plate and pentaprism is not avoided. In this paper, calculation method of non-common path error was proposed by contrast analysis between adjustment error and non-common path error in shearing interferometry, and non-common path error in surface measurement result was compensated. Lastly, experiment results demonstrate the surface result after compensation is in accordance with ZYGO interferometer.